Depth gauge

ABSTRACT

The invention relates to a depth gauge for use in angling or sports fishery. The depth of a body of water may be measured therewith from its surface to its bottom, and/or the depth and the size of strata of water of different temperatures for the purpose of offering bait to different species of fish in their preferred environments, for instance at the bottom of a water or at a thermocline stratum. In accordance with the invention, a water-proof housing a temperature sensor, a pressure sensor, a digital evaluation circuit, a display and a program switch are provided within a water-proof housing and electrically interconnected in such a manner, that the measurement value about the depth of the water to its bottom and/or water strata marked by temperature differences of more than 3° Kelvin are processed and stored by the digital evaluation circuit. By means of the program switch, the stored measurement data may be called up and rendered visible in the display. In its construction and configuration the depth gauge is optimally suited for its intended use. It is light and small, and it may be industrially manufactured with little investment.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a depth gauge for use in angling and sportsfishing. It is used to measure the depth of a body of water from itssurface to its bottom, or the depth of strata of water of differenttemperatures within a body of water.

2. The Prior Art

A digital depth gauge with a piezoresistive pressure recording(Druckaufnahme), integral illumination and zero point correction isknown for diving in mountain lakes having depths up to 200 m (Germanpatent specification 31 45 158 A1).

Owing to its structure, its size and its weight, as well as, inparticular, its elaborate set-up, this apparatus is unsuitable foranglers and sports fishermen.

Also an apparatus is known for detecting the profile of the bottom ofwaters which in essence consists of a pressure measuring capsule adaptedto be moved by a line on the bottom of the water in direct contacttherewith, the measured values of which are continuously transmitted toan interpreting station by a connection (German utility model 76 05605.8). This apparatus is utilized particularly in the preparation ofaqueous construction operations and is unsuitable in sports fishery.

For angling and sports fishing, species-specific bait has to be offeredto a fish in its respective environment, for which purpose the depth ofthe water has to be correctly determined by the angler or sportsfisherman. At present, this is done by repeatedly sinking and retrievinga ground lead (sinker) on a fishing line and a quill spaced therefrom,and by resetting the distance between sinker and quill until thedistance between the bottom of the water and the surface of the water isrecognizable by the position of the quill. This is a tedious andtime-consuming procedure which because of the frequent casting of thesinker may lead to fish being chased away.

It is known that in almost all bodies of waters there are strata orcurrents of cold and warm water. At the interfacial zones of such layersof water, i.e. at those positions at which the cold and warm waterstrata converge, there exist temperature differences of several degreesKelvin. Such strata are known to anglers and sports fishermen asthermoclines. These thermoclines are of particular importance to theangler or sports fisherman because it is these strata which are oftenfrequented by predatory fish. Therefore, the angler and sports fishermanfavors placing his bait as precisely as possible at or in thesethermoclines.

Unless the very elaborate procedure for determining these thermoclinesis wholly dispensed with and angling is to be undertaken on the basis of"pure luck", this thermocline can only be fathomed with a thermometer.This is done by systematically and frequently placing a thermometer atdifferent depths of the water, and retrieving it for reading, until theapproximate depth of the searched-for thermoclines has been determinedan the basis of a predetermined discontinuity in temperature.

The use of a known thermometer for this purpose is disadvantageousbecause of the disproportionately elaborate effort, which is why anglersand sports fishermen usually dispense with determining thermoclines inthe waters. In the event, the manipulation of a thermometer forfathoming thermoclines is only possible from a boat, so that from theland the angler has no possibility whatever for detecting thermoclines.

OBJECTS OF THE INVENTION

It is an object of the invention to provide a depth gauge for anglersand sports fishermen which is useful for measuring the depth of a bodyof water from the surface thereof to its bottom and/or for detecting thedepths of layers of water of different temperatures, and which is simpleand handy, which delivers reliable measurement values in the range ofrelatively shallow depths of water, and which may be manufactured withlittle investment in a cost efficient manner.

SUMMARY OF THE INVENTION

In accordance with the invention the object is accomplished byarranging, within a water-proof housing, at least an electrical pressuresensor, a display including a maximum storage, an electrical battery anda program switch, the pressure sensor being connected to the exterior ofthe housing unilaterally by at least one pressure compensation apertureor directly, the pressure sensor, battery, program switch and displaybeing electrically interconnected in a conventional manner such that themeasurement values of the pressure sensor are rendered visible in thedisplay and remain visible in the display until manually reset by theprogram switch.

In addition, at least one electrical temperature sensor and one digitalevaluation circuit may be arranged within the housing which in a knownmanner may, if required, be connected to other electronic componentssuch that the measuring values from the temperature sensors may beevaluated by the digital evaluation circuit as the depth gauge is beingsubmerged such that at an occurrence of a temperature discontinuityexceeding 3° Kelvin over a certain distance, the depth of the water atthat location is measured and recorded. Also, the measured value isrendered visible in the display where it remains visible until manuallyreset by the program switch.

In one embodiment of the invention the digital evaluation circuit may beconventionally interconnected with the measuring transducers, pressuresensor and temperature sensor, a measurement value storage, the programswitch as well as the display in such a manner that different measuredvalues representing water depth, the depth of the thermocline and itssize, the upper and lower temperature of the thermocline as well astemperatures prevailing at different depths can be stored and that thesemeasured values may be rendered visible in the display by manual programswitching.

The housing is provided with an eyelet and a bore for attaching afishing line or a plumb line. The housing may also consist of twothreadedly connectable portions, one housing portion being structured asa cavity for receiving ballasts of similar or different weights. Forpractical purposes, the cavity is provided with apertures for thecompensation of pressure.

Alternatively, the ballasts may be structured as parts fitting thehousing and may be attached to the exterior of the housing.

The depth gauge in accordance with the invention is optimally structuredto accommodate its intended purpose. It is small and light, simple touse and reliable in its performance. The use of such an apparatusreduces the effort involved in preparing for angling and improves thepossibility of success and, hence, the enjoyment of leisure time.

The depth gauge may be manufactured in different variants withrelatively small investment and at a reasonable ratio of price andperformance.

The invention will hereinafter be explained in greater detail. Example 1relates to measuring of the bottom of a water body and example 2 relatesto the measuring of thermoclines.

DESCRIPTION OF THE DRAWING

The drawing is a schematic rendition of the depth gauge in accordancewith the invention.

DETAILED DESCRIPTION OF THE INVENTION Example 1

The depth guage in accordance with the invention is provided with twohousing sections 1,4 which are screwed together by threading 6. Thehousing section 4 is structured as a cavity and is provided withpressure compensation apertures 3.

The housing section 1 contains a pressure sensitive electrical pressuresensor 8, an electric battery 9, a display 10 and a program switch 11.

The pressure sensor 8 seals one side of the housing section 1unilaterally relative to a chamber provided with pressure compensationapertures 2. An eyelet 13 is arranged on the housing section 1. Pressuresensor 8, battery 9 and display 10 are electrically interconnected in aconventional way and calibrated such that changes in pressure registeredby the pressure sensor 8 are rendered visible on a scale in the display10, and remain visible by virtue of a maximum storage until theindication in the display 10 is manually reset.

For using the depth gauge, it is attached to a fishing line by theeyelet 13. The housing sections 1 and 4 maybe separated, and ballouts 5are put into the cavity of the housing section 4 as determined by theangler. The housings sections 1 and 4 are then joined again, and thedisplay 10 is set to zero by the program switch 11.

The depth gauge affixed to the fishing line is now sunk to the bottom ofthe water at the location to be measured, with the water pressure whichis proportional to the depth of the water acting on the pressure sensor8 through the pressure compensation apertures 2, rendering the measuredvalue visible in the display 10 by means of the electric circuitry. Bymeans of the maximum storage the measured value will remain visible inthe display 10 until the depth gauge is withdrawn from the water, hasbeen read by the angler and reset by the program switch 11. On the basisof the measured value the relationship between the bait and the quillmay now be set precisely and in accordance with the species of fish tobe caught.

Example 2

The housing section 1 is threadedly connected to the housing section 4.The housing section 4 is hollow and is provided with pressurecompensation apertures 3. It may be charged with ballasts 5.

In the housing, there are provided an electrical pressure sensor 8, anelectrical temperature sensor 7, a digital evaluation circuit 12, anelectric battery 9, a program switch actuable from the exterior, and adisplay 10 as well as apertures 2 for the pressure sensor 8 and theaperture for the temperature sensor 7. The electric, electronic andmechanical structural units or components are electricallyinterconnected in a conventional manner in such a way that measuredvalues from the pressure sensor 8 and from the temperature sensor 7 maybe processed and stored by the digital evaluation circuit 12. Differentstored measured values processed by the evaluation circuit 12 may becalled up by the externally actuable program switch 11 from themeasuring data storage, and rendered visible in the display 10.

On top of the housing 1 there is provided an eyelet 13 for affixing aplumb line.

For use, the depth gauge is affixed to a fishing or plumb line by theeyelet 13, activated by the program switch 11, and sunk into the water.The values measured by the pressure and temperature sensors 7; 8 areprocessed by the digital evaluation circuit 12 and the depth at which atemperature discontinuity of more then 3° Kelvin occurs is particularlyregistered and stored.

When retrieving the depth gauge measurement data of the deepestmeasuring point of the water are no longer registered and stored. Themeasurement data processed and stored by the digital evaluation circuit12, in particular the discontinuity in temperature at a measured depth,can now be called up from the data storage by the program switch 11 andrendered visible in the display 10, when the depth gauge has beenretrieved from the water.

On the basis of this data, the angler may now place his species-specificbait for fish assumed at or in the thermocline and thus influence hischances of success in a positive manner.

I claim:
 1. An apparatus for measuring the vertical extent and thetemperature of at least a portion of a body of water, comprising:firstand second means for forming a housing; means for releasably connectingthe first and second means for forming a cavity within said housing;means in at least one of the first and second housing forming means formeasuring the pressure of the body of water as a function of thevertical extent and for deriving a first signal representative thereof;means in the one housing forming means connected to the pressuremeasuring means for storing the first signal; means in the one housingforming means for measuring the temperature of the body of water atleast within the vertical extent and for deriving a second signalrepresentative thereof; means in the one housing forming means connectedto the temperature measuring means for storing the second signal; meansin the one housing forming means for processing the first and secondsignals; means in the one housing forming means for selectivelyrendering the processed signals perceptible as values representative ofthe vertical extent and of the temperature; means in the other of thefirst and second housing forming means for receiving means for varyingthe weight of the depth gauge; and means mounted on at least one of thefirst and second housing forming means adapted to be connected to meansfor retrieving the apparatus from the body of water.
 2. The apparatus ofclaim 1, wherein said water pressure measuring means is exposed toambient water by means forming at least one aperture in said one housingforming means.
 3. The apparatus of claim 1, wherein said temperaturemeasuring means measures predetermined temperature differences over apredetermined vertical distance.
 4. The apparatus of claim 3, whereinsaid water temperature measuring means measures temperature differencesof at least 30° K.
 5. The apparatus of claim 1, wherein said means forrendering said signal perceptible comprises alph-anumeric indicatormeans.
 6. The apparatus of claim 5, wherein the alpha-numeric indicatormeans is provided with program switch means for selectively renderingvalues of the vertical extent and of the temperature visible and forresetting the values to predetermined values.
 7. The apparatus of claim1, further comprising battery means in the one housing forming means andelectrically connected to the first and second signal deriving means,the storing means, the rendering means, the resetting means and thesignal processing means.
 8. The apparatus of claim 1, wherein thereceiving means comprises a fishing line.
 9. The apparatus of claim 1,wherein said first and second housing forming means are threadedlyconnectable to each other.
 10. The apparatus of claim 1, wherein themeans for measuring the temperature of the water is responsive totemperature changes of about 30°.